Elastic and miniaturized joints or hinges are known in the state of the art. Said hinges are used in particular in the case of extra flex eyeglasses. The term “extra flex hinges or joints” means, in particular, hinges or joints in which the rotation of a hinge element in relation to the other hinge element is regulated by elastic means, like for example springs or similar means. In particular, the rotation of a hinge element in relation to the other hinge element and therefore, in the particular case of eyeglasses, of one part of the eyeglasses in relation to the front of the eyeglasses, is obtained by counteracting the elastic force of said elastic means or springs. Due to the elastic force, therefore, one hinge element tends to return to predefined positions, and therefore, for example, the temples of a pair of eyeglasses tend to return to predefined positions. For example, the elastic means will tend to maintain the temples of a pair of eyeglasses in the position in which the eyeglasses can be worn; if the temples are moved from this position, they will return to their original position as soon as they are released thanks, in fact, to the action of the elastic means. The above applies also to the case where the temples are folded, for example in the position suited to allow the eyeglasses to be placed in a case. The opening of the temples can be achieved by counteracting the action of the elastic means. The temples will assume the complete opening position if they are rotated by a minimum angle, beyond which the elastic means will force them into the open position. If, on the other hand, the rotation angle is smaller than said minimum angle, when the temples are released they will return to the folded position. The hinges of the extra flex type also allow the temples to be opened beyond the open position (that is, the position that allows the eyeglasses to be worn), and therefore in such a way as to define an angle that is larger than 90° with respect to the front portion of the eyeglasses. As previously explained, when the temples are released, thanks to the action of the elastic means they automatically return to the maximum opening position, in which each one of the temples defines an angle of substantially 90° with the front portion of the eyeglasses.
In the design and development of hinges for eyeglasses, in particular in the design and development of miniaturized elastic hinges, even of the extra flex type, for eyeglasses, there are many factors to be taken in consideration, as the functions that the hinges of this type must perform and guarantee are multiple and different from one another.
A first factor is aesthetic, as the hinges must not be too cumbersome and therefore not too visibile, so that they must be housed partially inside the front portion of the eyeglasses and partially inside the corresponding temple or side. A second factor is related to mechanical reliability, as the hinges or joints must on one side allow the desired rotations and on the other avoid undesired rotations. Furthermore, the hinges must guarantee a minimum duration and be free from breakages or drawbacks that affect their operation, in such a way as to limit repair costs as much as possible. Always with reference to their mechanical reliability, they must guarantee the stability of their open or closed position, as well as the automatic return to said open or closed positions when they are rotated. Rotation plays or slacks must also be avoided in every position of the hinge, and therefore of the temple with respect to the front portion of the eyeglasses. Even after a relatively long time of usage said plays or slacks should not be present. It should also be possible to adjust the hinges so as to adapt them to special needs or conditions of use. The application or assembly of the hinges, for example on eyeglasses, should possibly be simple and quick, so as to ensure savings in the assembly costs. Also the assembly of the hinges should possibly be simplified, so that the number of component parts may be reduced, in any case guaranteeing the functionality characteristics described above. Finally, in particular in the case of extra flex hinges, they must allow an extra opening angle that is wide and constant over time.
In the state of the art it is known that the manufacturers of miniaturized elastic joints and hinges, as well as the manufacturers of eyeglasses, have made many attempts to design and produce hinges and joints capable of satisfying the needs described above; unfortunately, however, the various attempts made have not achieved the desired results. For example, in the cases where the aesthetic aspect has been privileged, thus opting for simple solutions form the technical point of view, for example characterized by a reduced number of component parts and therefore not too cumbersome, said solutions have proved to be insufficiently reliable from the mechanical point of view, delicate even though simple, and limited from the point of view of performance in terms of rotation capacity, amplitude of the opening angle and elasticity. On the contrary, the solutions in which the mechanical aspect has been privileged and which are therefore characterized by fine mechanics and by a high number of component parts have proven to be unsatisfying or even impracticable because they were bulky and unsuited to be hidden or hardly visible and to be housed in the parts of the eyeglasses. Other solutions, that on the other hand are quite satisfying from the aesthetic point of view, have proven to be difficult to assembly and therefore impracticable due to the high costs involved.
By way of example, it is possible to refer to a solution known in the state of the art, characterized by limited size and overall dimensions and provided with a flex mechanism, suited to be mostly housed in the parts of the eyeglasses and therefore to be hidden or hardly visible. This solution or mechanism, however, does not allow the elastic means to be made more rigid, unless the dimensions of said mechanism are increased, so that its application to relatively heavy eyeglasses, like the ones that could be naturally combined with this type of mechanism, makes the temple unstable in its fixed positions (open and closed). The mechanism according to this solution, furthermore, can be neither set nor adjusted, as the two base elements that make it up, which are suited to be respectively fixed to the front portion and to the temples of the eyeglasses, are connected to each other by means of a small pin instead of a screw. The replacement of this pin, if it should break or be lost, would be difficult if it had to be carried out with tools usually available to both the final user or a technical expert in the field, for example an optician. This solution, therefore, does not meet the need to guarantee simple assembly and maintenance. Finally, in the mechanism carried out according to this solution, the elastic element (spring) is located in a definitely unstable position, so that in case of impact it could move out of its seat and thus affect the functionality of the eyeglasses. The mechanism carried out according to this solution, therefore, does not meet the need for mechanical reliability, either.
According to another solution known in the state of the art, the mechanism proposed is intended to be permanently assembled by the user. This prevents many users from using it. The assembly of the mechanism, independently of whether it is carried out by the final user or by a technician, is extremely complex, since the same mechanism comprises a box-shaped element in which two distinct and therefore not interchangeable elements must be inserted, which must be kept in position through the application of a lid (to be applied to the box-shaped element) that is difficult to handle and must be oriented in a predefined way. Furthermore, regarding the application of the mechanism to eyeglasses or similar accessories, it must be noted that once the assembly of the front and the temple of the eyeglasses has been completed (with the mechanism interposed between them), the front and temple feature an unacceptable rotation play or slack that would be further amplified in case of application to eyeglasses with rather large temples. The mechanism carried out according to this further second solution does not include elements suited to ensure its mechanical locking, so that the possible applications of the same mechanism are limited only to the case of eyeglasses that allow a deformation of the temple and/or front portion. It is therefore necessary to exclude the application of the mechanism to eyeglasses made of rigid materials, like for example wood or natural materials in general. Finally, in case of application to eyeglasses made of deformable materials, said application is however difficult and mistakes are likely to be made, for example in the case of metallic materials or acetate.
Further examples of an elastic miniaturized hinge according to the prior art are known from documents EP2009484 A1, WO97/45763 A1, WO2004/040355 A1, EP1666952 A1, U.S. Pat. No. 7,264,349 B1, EP2120087 A1 and EP2163938 A1.